Magnetic record member



Jan. 2, 1951 M cAMRAS 2,536,029

MAGNETIC RECORD MEMBER Filed Deo. 5, 1946 F it 2 .5W/givin" Patented Jan. 2, 1951 UNITED S TA'lhS OFFICE MAGNETEG REICh-D Mlili/li Marvin Cainras, Chicago, lill., to lArmour Research Foundation of illinois institute of Technology, Chicago, llllg a corporation of Illinois Application December 5, lill-ti, Serial No. 714,236

3 Claims. (Cl. tid-Maine) This invention relates to a magnetic recorder 4method and meansand more particularly, to a moving picture film having a novel soundtrack the following description taken inconnection thereon andto novel apparatus for recording on `enable` asulcient amountof energy to be 1 `corded on the film without changing the c fventional dimensions of a The diiiiculty has been extremely great in this :connection where the sound track was to be used with 8 and 16 mm. film.

One of the principal features and objects of the present invention is to provide a novel sound track arrangement on a moving picture film which will enable sufficient energy to be recorded thereon and reproduced therefrom without enlarging conventional size film.

A further object of the present invention is to provide a novel sound head for an elongated flat record member, such, for example, as a nlm or tape. e

A still further object of the present invention is to provide a novel magnetic recorder method and means.

Another object of the present invention is to provide a novel magnetic record in which a magnetizable sound track is provided around one edge of a tape or film record member with a portion of the sound track lying on one of the flat surfaces of the tape, while a second portion having magnetic continuity with the rst porw tion lies on an edge surface of the tape or nlm.

Another and still further object of the present invention is to provide a novel e.ectro-magnetic transducer head having a shoulder portion in the magnetic polar portion over which record member rides and in which two surfaces at right angles to each other are effective in ,icing the record member or reproducing a record pre viously magnetically recorded on the record memu ber.

The novel features which I believe to be characteristic of my invention are set forth with parA ticularity in the appended claims. My invention itself, however, both as to its organizaron, man ner of construction and method of operation, together with further objects and advantages thereof, may best be understood by reference to with the accompanying drawing, in which:

Figure l is :a diagrammaticvsketch of a piece oi. motion picture film;

1Figure 2 is a vertical sectional View of a film such as that illustrated in i'ligure l` riding over an oil-damped flywheel and in engagement with electro-magnetic transducer head; and

a diagrammatic side view `of an eti-3 transducer head and erase head ith which they are associated.

yvlfliile the novel principles of the present inveni tion are not limited to moving picture iilm, they are particularly applicable to a film Such as the film lll illustrated in Figure 1 of the drawing. This nlm lo includes a main body portion II formed of cellulose nitrate or cellulose acetate and is provided with a series of sprocket holes I2 which are located between the picture frame I3 and an edge it of the film I0.

As may be seen best in Figure 2 of the drawing, a magnetic sound track I5 is coated over a portion of the upper surface of the film Il] between the sprocket holes I2 and the edge I4 as well as around the adjacent corner and down over the edge surface of the film. This gives a substantial surface area for the magnetic sound track Without the disadvantage of having to bring the sound track up to the edge of the sprocket holes I2.

As is well known to those skilled in the art, the punching of the sprocket holes I2 in the` film I0 causes a stressing of the film in the immediate region of the sprocket holes which results in a very bad effect on the magnetic sound track I5 when the sound track is brought into this region of stress.

An electro-magnetic transducer head I6 having a pair of polar portions I'I is arranged to ride on the sound track l5 of the lm ID. These polar portions il include a longitudinally extending shoulder portion i8 having a side wall I9. The shoulder portion i8 is arranged to ride on top of the sound track i5, while the wall portion I9 is arranged to ride against the portion of the sound track I5 which lies over the side edge I4 of the film lll.

The electro-magnetic transducer head I6 is spring-pressed by means of a leaf spring 20 or other suitable mounting mechanism which is carried on a supporting structure 2l. This spring means 2li resiliently urges the head I6 against the nlm as the film lil rides over an inertia member 2l mounted for rotation on the axis 22. This inertia member may be an oil damped flywheel or other suitable stabilizing member or capstan.

The electro-magnetic transducer head I8 also includes a signal coil 23 and a high frequency biasing coil 24 which are, respectively, energized through conductors 25 and 26. The high frequency biasing coil 24 is preferably connected in series with an erase coil 21 which is mounted on an erase head 28 similar to the electro-magnetic transducer head I6 but having a slightly larger spacing between the pole portions I1. The erase head 28 is also resiliently mounted on a leaf spring 29 carried on the supporting frame 2|.

It has been found that the above described arrangement and technique is so efficient that satisfactory results may be obtained even on 8 mm. lm, notwithstanding the low speed and the extremely small size of the latter. It will also be observed that the inherent nature of the shouldered portions of the head structure is such that the head is self-aligned with the edge of he lm.

While I have shown a particular embodiment of my invention, it will, of course, be understood that I do not wish to be limited thereto, since many modifications may be made, and I, therefore, contemplate by the appended claims to cover al1 such modifications as fall within the true spirit and scope of my invention.

I claim as my invention;

l. A magnetic record member comprising a non-magnetic carrier having a coating of a magnetizable material thereon forming two sound track portions, said sound track portions being in thin strips and lying in two planes substantially at right angles to each other forming an L-shape cross-section and having magnetic continuity Ywith each other, one of said sound track portions lying on an edge surface of said carrier and the other sound track portion lying on an adjacent face portion of said carrier, whereby a sufficient amount of energy may be recorded on said nonmagnetic carrier for reproduction therefrom.

2. A moving picture film having a line of sprocket holes spaced from one edge thereof and having a coating of magnetizable material thereon forming a, magnetic sound track of L-shape cross-section disposed around a corner edge of said lm, whereby a sufcient amount of energy may be recorded on said moving picture film for reproduction therefrom.

3. A moving picture lm having a line of sprocket holes spaced from one edge thereof and having a coating of magnetizable material thereon forming a magnetic sound track of L-shape cross-section disposed on the side edge surface of said lm adjacent said sprocket holes as Well as on the marginal main surface of said film over a region extending from said one edge to a point spaced short of said sprocket holes, whereby a suiiicient amount of energy may be recorded on said moving picture lm for reproduction therefrom.

MARVIN CAMRAS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,156,976 Clement Oct. 19, 1915 1,466,750 Peterson Sept. 4, 1923 1,883,561 Chipman Oct. 18, 1932 1,883,562 Chipman Oct. 18, 1932 1,949,840 Languekin Mar. 6, 1934 2,210,770 Muller-Ernesti Aug. 6, 1940 

